Application of the transmission line matrix method to the calculation of the shielding effectiveness for metallic enclosures

The ability of an enclosure to reduce the emission or to improve the immunity of electronic equipment to high frequency interference is characterized by its shielding effectiveness (SE), which is defined as the ratio of the field in the presence of the enclosure to that in its absence. EMC regulatory requirements make the efficient analysis of shielding effectiveness very important in the development of microwave circuits. The SE of a metal enclosure is determined mainly by its general shape and the shape of its apertures. In this paper, an efficient method is presented for the analysis of the shielding effectiveness in high frequency communication circuits based on the transmission line matrix (TLM) method. Since the formulation is in the time domain, wide band effects are easily and accurately modeled. The comparison of the results obtained from the proposed numerical method with those obtained from measurement show that the TLM method gives more accurate results than other methods reported in the literature.